Extending the Soundcard for Use with Generic DC Sensors Demonstrated by Revisiting a Vintage ISA Design

Dimitrov, Smilen

Proceedings of the International Conference on New Interfaces for Musical Expression

The sound card anno 2010, is an ubiquitous part of almostany personal computing system; what was once considereda high-end, CD-quality audio fidelity, is today found in mostcommon sound cards. The increased presence of multichannel devices, along with the high sampling frequency, makesthe sound card desirable as a generic interface for acquisition of analog signals in prototyping of sensor-based musicinterfaces. However, due to the need for coupling capacitorsat a sound card’s inputs and outputs, the use as a genericsignal interface of a sound card is limited to signals not carrying information in a constant DC component. Through arevisit of a card design for the (now defunct) ISA bus, thispaper proposes use of analog gates for bypassing the DCfiltering input sections, controllable from software — therebyallowing for arbitrary choice by the user, if a soundcardinput channel is to be used as a generic analog-to-digitalsensor interface. Issues regarding use of obsolete technology and educational aspects are discussed as well.